DF150 exceeding max RPM.

[BKF1972]

Hi all

With 2 pers. on board, my engine exceeds the max RPM limit with WOT and max trim.

My propeller is a stainless steel 3 bladed 21' and it runs between 6200 - 6400.

Obviously my propeller hasn't the proper size so I was considering to replace it.

Any recommendations?

[kmoose]

A 4 bladed 21 would knock it down a little but a 23 , 3 blade would probably be your best option. What type of hull and boating do you do? inshore, offshore, lake or river? Also, what brand of prop are you running? Is the boat or motor new, or just new to you? The dealer or re-power center should confirm correct prop selection before the deal is complete so that might be an option as well.

[Harper]

You could possibly go a bigger diameter, although you don't mention the diameter of your present prop. My DF150 has a SS 3 blade 18 1/2 pitch, but it's a 16" diameter, and pushes my 20 footer just about right. Also you don't mention whether you're talking SS or aluminum, and that, too, will make a difference. I get 6000 rpm with two on board, usual equipment, and 60 gal fuel, but put two more people on board and it drops to about 5800 max. One more thing I'm not sure I understand about your post - WOT and max trim Do you mean you have it trimmed as high as it will go before going into tilt? I don't know about your boat, but there's no way mine will run at WOT and max trim without being at least marginally into some prop ventilation.